I am currently trying on a synthesis involving Amberlyst-15 (polystyrene with sulfonic group at p-position) as a proton donor. When following the reaction process by quantitative 1H NMR, I am noticing that part of my (basic) reactant (2-methylimidazole) is being immobilised against the resin and is unavailable for reaction with the rest of the reactants.
Has anyone experienced this when working with similar ion excange resins?
I am trying to figure out ways to liberate it from the resin. Any suggestions would be greatly appreciated.
This might be due to hydrolysis by Amberlyst-15 resin as a acid catalyst.
Dear Trey Todor Koev thanks for sharing this very interesting technical problem with the RG community. I'm absolutely no specialist in this field, so perhaps my thoughts are a bit naive. I assume that you just have an acid-base reaction in which the 2-methylimidazole formed a tightly bound sulfonate salt with the ion-exchange resin. In this context, please have a look at the following potentially useful article which might help you in your analysis:
Anchoring a Co/2-methylimidazole complex on ion-exchange resin and its transformation to Co/N-doped carbon as an electrocatalyst for the ORR
Article Anchoring Co/2-methylimidazole complex on ion exchange resin...
Unfortunately this paper is not freely available as public full text on RG. However, all ten authors have RG profiles, so that it should be no problem to request the full text of the paper dierctly from one of the authors via RG.
Good luck with your work!
Thank you Frank T. Edelmann , much appreciated! It has been a while since I have worked with metal-organic complexes, but from what I understood, it is Co that is doing the coordination of 2-methylimidazole, as opposed to the resin adsorbing it. Perhaps I am misunderstanding the paper, but that is how it appears to me?
The only explanation I have is that somehow the sulfonic acid is reacting with 2-methylimidazole, so I will try to block the hydroxyl residue in the sulfonic group with large cations, and see if that leads to any less reactant loss.
Any further input would be much appreciated! :D Thank you all in advance!
Dear Trey Todor Koev thank you for your kind response and explanation. Attached please find the Supplementary Information of the article in which the experiments are described in detail. Indeed, the authors first do a reaction between the Amberlyst-15 and a cobalt(II) salt. Then the 2-methylimidazol is added which coordinates to the cobalt ion. Finally excess 2-methylimidazol is washed from the resin with methanol. I assume that in your case the Amberlyst-15 just forms a 2-methylimidazolium sulfonate salt which is tightly bound to the resin. What is the function of the Amberlyst-15 in your reaction anyway?
With best wishes, Frank Edelmann